Food-handling facility disinfection treatment

ABSTRACT

Food handling facilities such as meat packing, plants, dairies, kitchens and the like are disinfected using a disinfecting atmosphere which includes ozone and hydrogen peroxide, at a relative humidity of at least 60%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the national stage under 35 U.S.C. §371 ofInternational Patent Application No. PCT/CA2011/050544, filed Sep. 8,2011, designating the United States, and published Mar. 15, 2012 asInternational Publication No. WO/2012/031366, which application claimspriority to and the benefit of U.S. Patent Application Ser. No.61/380,758 filed on Sep. 8, 2010. The disclosures of theabove-identified applications are expressly incorporated herein by thisreference in their entireties.

FIELD OF THE INVENTION

This invention relates to bacterial disinfection treatments for foodhandling premises such as food processing rooms, meat packing plants,food packaging rooms, kitchens and the like. More particularly, itrelates to processes and systems for methods and systems fordisinfecting food handling premises of human-harmful, foodpoisoning-causing bacteria including Listeria species bacteria such asListeria monocytogenes and Salmonella species such a S. typhium,causative agents of food poisoning in humans and animals.

BACKGROUND OF THE INVENTION

Listeria is a genus of Gram-positive bacteria of the bacilli class. Itcontains six species, typified by L. monocytogenes, the causative agentof listeriosis, an uncommon but potentially lethal food-borne infection.L. monocytogenes is one of the most virulent food-borne pathogens.Listeriosis has been reported to be the leading cause of death amongfood-borne bacterial pathogens, responsible for about 2,500 illnessesand 500 deaths annually in the United States.

L. monocytogenes is commonly found in soil, stream water, sewage, plantsand food. Vegetables can become contaminated with L. monocytogenes fromthe soil. Uncooked meats, unpasteurized milk, products made fromunpasteurized milk such as certain cheeses, and processed foods commonlycontain Listeria. Sufficient heating and cooking will kill Listeria, butcontamination of food products can occur after cooking and beforepackaging. Meat processing plants, for example, producing ready-to-eatproducts such as deli meats and hot dogs, follow extensive sanitationpolicies to guard against listeria contamination.

Outbreaks of Listeria have reportedly been caused by hot dogs, delimeats, raw milk, soft-ripened cheeses, raw and cooked poultry, rawmeats, ice cream, raw vegetables and raw and smoked fish. Pregnantwomen, the elderly and those with compromised immune systems are themost vulnerable patients. In its early stages Listeria infection iseffectively treated with antibiotics such as ampicillin, ciprofloxacinand azithromycin, but it is commonly not recognized until a moreadvanced stage is reached. Prevention of such infections is accordinglyof high importance.

Salmonella is a large genus of bacteria, many species of which can causedisease if ingested by humans. Salmonella bacteria infections arecommonly termed “Salmonellosis” and are manifested by diarrhea,vomiting, fever and abdominal cramps (food poisoning). Among the humanharmful Salmonella species are S. enteridis and its sub-species, S.bongori and S. typhi, the human pathogen of typhoid fever.

BRIEF REFERENCE TO THE PRIOR ART

Effective sanitation of food contact surfaces is necessary to preventlisteria or salmonella infection. At present, this is done using alcoholas a topical sanitizer. Quaternary ammonium salts are used incombination with alcohol with increased duration Oxidizing agents(chlorine dioxide, peroxides, ethylene oxide, sodium hypochlorite andthe like) may be used to clean Listerium- or Salmonella-contaminatedsites, but these are relatively slow-acting. Such clean-up istime-consuming and costly, since the food handling facility must remainout of commission for extended periods of time. Soft and porous fabricsurfaces pose a particular problem, since they will harbor liveListerium or Salmonella bacteria and render them inaccessible to routineliquid or gaseous treatments. It is important that cleaning andsanitizing agents used in food treatment facilities leave no residueswhich might be harmful if ingested.

Vaporized hydrogen peroxide (VHP) is highly effective as a sanitizingagent when applied to smooth surfaces, but has little or no efficacy onporous materials and is of questionable value against thick biofilms ofa nature more characteristic of a food preparation area. Moreover, VHPis very damaging to electronic devices that may be present in the foodhandling facility.

Once a porous, soft surface such as carpet, drapery, porous material inceilings and the like becomes impregnated with bacteria, it cannot beeffectively disinfected using currently available agents and processes.

Ozone is known to be a powerful anti-bacterial, anti-fungal andanti-viral agent. For over 100 years, it has been used for waterpurification. It is known to be effective against Legionella Bacteria,E. coli and pseudomonas populations in such plants.

Canadian Patent 2,491,781 Lynn, issued Jun. 9, 2009, discloses use of ahigh pressure water stream and a high pressure ozonized water stream forcleaning and sanitizing objects such as surfaces and poultry carcasses.

Canadian Patent 2,473,540 Gibson and Hobbs, issued Dec. 2, 2008,discloses a ventilation system including a duct containing anultraviolet light source generating ozone in the air stream passingthrough the duct, the inlet to which is adjacent to a food cookingsource, so that purified air is emitted from the cooking environment.

It is an object of the present invention to provide a novel andeffective method of treating facilities and objects infected or prone toinfection with human-harmful, food poisoning-causing bacteria.

SUMMARY OF THE INVENTION

The present invention provides, from one aspect, a process of combatinghuman-harmful, food poisoning-causing bacteria in an enclosed space andon surfaces therein, which comprises exposing the bacteria in the spaceto a disinfecting atmosphere which includes ozone at a concentration of2-350 ppm by weight and hydrogen peroxide at an amount of 0.2-10 wt. %,at a relative humidity of at least 60%, and for a period of at least 30minutes sufficient for an effective kill of the bacteria; andsubsequently removing ozone from the atmosphere, down to 0.04 ppm orless.

Another aspect of the invention provides a portable system fordestroying human-harmful, food poisoning-causing bacteria, in rooms andon surfaces and equipment therein, comprising an ozone generator fordischarging into the room a gaseous mixture including ozone; an ozonecontroller adapted to control the amount of discharged ozone; a sourceof hydrogen peroxide for discharging controlled amounts of hydrogenperoxide into the room; means for discharging the hydrogen peroxide andozone into the room; humidity adjusting means adapted to increase ordecrease the relative humidity of the room during treatment; and anozone remover adapted to destroy ozone, down to a safe level in the roomatmosphere for subsequent human utilization.

BRIEF REFERENCE TO THE DRAWINGS

FIG. 1 of the accompanying drawings is a diagrammatic illustration of anapparatus in accordance with an embodiment of the invention, disposedwithin a room to be disinfected;

FIGS. 2A and 2B are diagrammatic illustrations of physical agitationsystems for use in embodiments of the invention;

FIG. 3 is a diagrammatic illustration of an apparatus according to theinvention, in portable, transportation mode;

FIG. 4 is a diagrammatic illustration of a test apparatus used togenerate some of the test results reported below;

THE PREFERRED EMBODIMENTS

Preferred ozone amounts for use in the invention are from about 10-350parts per million in the disinfection atmosphere, more preferably20-350, or 20-200, or 20-100, or 35-100, or even more preferably 20-90parts per million in the oxygen/ozone gas mixture, and most preferably35-80 ppm ozone. Preferred amounts of hydrogen peroxide are the amountssupplied to the disinfecting atmosphere using an aqueous solutioncontaining 0.2-10%, more preferably 0.5-10%, or 0.5-7%, or 0.5-5%, or1-5%, or 1-3% hydrogen peroxide. In the description below, the peroxidepercentages used are sometimes expressed in terms of these solutionpercentages. The amounts are chosen so that no serious deleteriouseffects are suffered by other equipment in the treatment room to whichthe disinfecting atmosphere is supplied. The amount of hydrogen peroxidein the disinfecting atmosphere can be calculated from the volume ofaqueous hydrogen peroxide evaporated into the disinfecting atmosphere,the volume of the room being disinfected and the concentration ofhydrogen peroxide in the starting solution. Times of exposure of theroom and its surface to the disinfecting atmosphere are suitably from 15minutes to about 120 minutes, preferably from about 60 to about 105minutes, and most preferably about 90 minutes. These times areconstrained to some extent by the need to clear the room of ozone (downto a maximum of 0.04 ppm) following the disinfection phase, and returnthe room to normal use within a reasonable period of time, with theentire start-to-finish time not exceeding 150 minutes. The ozone removalis an extremely rapid and fully effective process. Both the hydrogenperoxide and the ozone (and any products of interaction between them)should be removed before the room is put back into normal use.

The preferred portable system for destroying human-harmful, foodpoisoning-causing bacteria according to the present invention includes,as part of its means for discharging the hydrogen peroxide and ozoneinto the room, a dislodgement system at the outlet end of thedischarging means. The dislodgement system allows penetration of carpet,drape and similar porous surfaces in the room, to gain access toconcealed/sequestered colonies of the bacteria, and to attack thebacteria protected by a biofilm formed on surfaces in the room andembedding the bacteria and spores therein. The dislodgement system canbe manually operated, with operators protected by a hazard suit andmask, or remotely operated or totally automated. It may take the form ofone or more outlet jets, with associated manually operable jet pressurecontrols. It may take the form of a revolving or fixed brush withbristles of appropriate stiffness, alone or in combination with anoutlet jet. Any form of dislodgement system effective to disturb thepile of carpet fabrics, upholstery fabrics and the like so as to accessthe remote parts which might harbor anthrax spores or colonies can beused. This includes non-physical applications such as air jets,ultrasonic energy radio-frequency energy and electromagnetic waves, forexample, capable of causing physical disruption and which result inmicro-physical movements of fibrous surfaces.

The ozone for use in the present invention can be generated by any knownmeans. In the case of corona or other electrical discharge generationfrom oxygen, the apparatus of the invention preferably includes acontainer of medical grade oxygen. The oxygen container can be astandard, pressurized vessel containing medical grade oxygen, of thetype commonly found in medical facilities. Oxygen from this container isfed to an ozone generator, where the oxygen is subjected to electricaldischarge, normally with high voltage alternating current, to convertsmall amounts of the oxygen to ozone and produce a gaseous mixture ofoxygen and ozone. The quantity of ozone in the mixture is controllableby adjustment of the voltage of the electrical discharge. Suitable ozonegenerators are known and available commercially. The relative amounts ofozone generated are relatively small, expressed in parts per million(ppm), but such is the power of ozone as a disinfectant, especially incombination with hydrogen peroxide in accordance with this invention,that such small quantities thereof are all that is required.

Alternative forms of ozone generation can be used if preferred.Ultraviolet radiation of appropriate wavelength, incident upon oxygen orair, is one acceptable alternative. In such a system, air from the roomitself may be fed into the ozone generating unit to supply the requiredoxygen for conversion to ozone. Other methods of ozone generation whichcan be used include photocatalytic reactions, cold plasma, etc.

The relative humidity of the disinfecting atmosphere in the treatmentspace should be at least 60% and preferably at least 65%, for effectivedisinfection. To ensure this, one can incorporate a humidifier in thesystem of the invention, using sterile water from an internal systemreservoir to adjust and control the humidity of the issuing gas mixture.In this way, desirable humidity for most effective disinfection isachieved at the point of discharge where dislodgement of a carpet ordrapery surface can take place. Since the adjustable humidifier needonly increase the humidity of the space to the desirable level, however,it can be placed in any location within the space. In one embodiment, hehydrogen peroxide vapor is applied, in controlled amounts, to theair/water vapor issuing from the humidifier and thus added to theozone/oxygen containing gas mixture. Alternatively, hydrogen peroxidecan be applied to the water used to humidify the target location.Hydrogen peroxide is commercially available as aqueous solutions ofstandard concentrations of hydrogen peroxide. For use in embodiments ofthe present invention, a standard solution of known peroxideconcentration is suitably diluted down by a fixed volume of distilledwater. The peroxide load is standardized based on the known volume ofwater from the peroxide solution required to raise the relative humidityto the desired extent, e.g. from 40-80%. From this, the amount ofhydrogen peroxide in volume % or ppm by volume introduced into thetreatment facility can be calculated.

Certain systems according to embodiments of the invention may include atemperature adjuster and controller for the gas mixture. This can be asimple heater/cooler through which either the incident oxygen or thegenerated oxygen/ozone mixture passes prior to discharge into the roomatmosphere. While simple adjustment of the temperature of the room usingan external room heating system and thermostat can be effective, it ispreferred to adjust the temperature of the issuing gas mixture, for mosteffective treatment of the carpet and drapery surfaces. The ideal rangeof temperature for ozone and ozone/hydrogen peroxide decontamination ofListeria is 15° C. to 30° C.

The system of the invention also preferably includes an ozone removalunit. Such units are known, and can be purchased commercially for use inthe present invention. Depending on the volume of the room atmosphereand the capacity of the ozone removal unit, more than one such unit maybe incorporated in the system of the invention. Suitable ozone removalunits are those based on activated carbon as the removal medium. Theseact very quickly, and do not lead to the formation of hazardous reactionproducts. The inclusion of such units enables the treated facility to becleared of ozone and returned to normal use rapidly, for economicreasons. Other types include systems based on catalysts such asmanganese oxide or other metal oxides, which may be heated to removemoisture, thermal destruction in conjunction with other metals includingplatinum or palladium.

Human-harmful, food poisoning-causing bacteria to which the presentinvention is particularly suitable include Listeria species such asListeria monocytogenes, and Salmonella species such as S. typhium and S.enterides.

FIG. 1 of the accompanying drawings shows a room 10 such as a room of afood processing facility liable to Listeria bacterial contamination andclosed ready for disinfection by a process according to an embodiment ofthe invention. The room is substantially hermetically sealed. Inside theroom is a pressurized cylinder 12 of oxygen, feeding oxygen gas into ahumidifier 14 and thence to an ozone generator 16, which includeselectrical discharge plates of variable voltage to adjust the quantityof ozone which is generated. A heater and a pressure controller (notshown) may be disposed near the entrance to the ozone generator. Outputof oxygen/ozone gas mixture is via room outlets 18, 20 to the atmosphereof the room 10, and via wands 22A and/or 22B to a dislodgement means inthe form of scrubbing brushes 24A and 24B mounted on the outlet ends ofthe respective wands 22A, 22B. The heater, the pressure controller, thevoltage supplied to the ozone generator 16 and the humidity levelsupplied by the humidifier 14 are all controlled and adjusted from anexternal control panel 26 via respective electrical connections 28, 30,32 and 34. Also disposed within the room is an oscillating fan 34 and anozone destruct filter unit 36.

Disposed within the room 10 is a container of aqueous hydrogen peroxidesolution 19 and associated air blower 21 which, during operation, blowsvaporized hydrogen peroxide in controlled amounts into discharge wand22A and 22B to mix with the output of ozone/oxygen therein. The amountof hydrogen peroxide being supplied is controlled by adjustment of theblower 21 through a connection thereof to the control panel 26. In analternative arrangement, hydrogen peroxide can be supplied fromgenerator 19 to the humidifier 14.

FIGS. 2A and 2B of the accompanying drawings show in more detail formsof dislodgement means 24A and 24B for use in the present invention,attached to the outlet, discharge ends of respective wands 22. Thedislodgement means 24A has a jet outlet nozzle 38A at its extremity, anda generally circular plate 40 mounted on the wand 22A near the dischargeend. The wand 22A passes through a central aperture 42 in a plate 40.The plate 40 has brush bristles 46A mounted on its lower surface,arranged in two arcs around the jet outlet nozzle 38A and protrudingdownwardly to an extent just beyond the extent of outlet from nozzle38A. In use, oxygen/ozone gas mixture or oxygen/ozone/hydrogen peroxidegas mixture issues from nozzle 38A at relatively high pressure, and canbe directed by the operator holding the wand to a carpet surface areawhile at the same time the operator scrubs the carpet surface area withthe bristles 46A.

FIG. 2B shows an alternative but essentially similar arrangement, inwhich plate 40 is replaced by a wheeled platform 44 carrying two rotarybrushes 46B and three gas jet outlets 38B for the oxygen/ozone/hydrogenperoxide delivery at pressure, located forwardly of the rotary brushes46B.

FIG. 3 of the accompanying drawings illustrates the portability of asystem according to the invention. Parts are numbered as in FIG. 1. A4-wheeled cart 48 is provided, on which all the component parts of thesystem can be loaded for ease of transportation from one room toanother. The instrumentation and control panel can be disconnected fortransportation, and re-connected and disposed outside when the apparatusis placed in another room for use as shown in FIG. 1. The cart 48 isremoved while the system is in use, but is loaded with the componentsafter use, either for transportation to another room or for storage.

The operation of the system will be readily apparent from the precedingdescription of its component parts and their inter-connection. The cart48 carrying the component parts is wheeled into the room 10 to bedisinfected, and the parts are distributed around the room and connectedtogether as illustrated in FIG. 1. An operator wearing a hazard suit andother appropriate protective clothing enters the room and holds the wand22. The room is sealed. Conditions of treatment are set on the controlpanel 26, and the apparatus is switched on so that oxygen/ozone/hydrogenperoxide gas mixture at controlled ozone concentration, hydrogenperoxide concentration, relative humidity, temperature and elevatedpressure issues from jet nozzle 38. The operator applies the jetted gasmixture to the carpet surfaces, drapery surfaces and other absorbentsurfaces in the room, scrubbing the surfaces at the same time with thebristles 46. The room becomes pressurized above atmospheric pressure,due to the introduction of the oxygen/ozone gas mixture. Pressure iscontinually monitored by the control panel 26 to ensure safe workingconditions for the operator, as well as the temperature, humidity andozone concentration in the room. Smooth surfaces in the room may notneed the action of the dislodgement means, but are satisfactorilydisinfected by contact with the disinfecting atmosphere in the room. Theoscillating fan 34 is operated throughout the procedure, to circulatethe oxygen/ozone mixture throughout the room.

After a pre-set time of the procedure, and after all the appropriate,absorbent surfaces have been scrubbed, a time not normally exceeding 90minutes, the hydrogen peroxide supply, the oxygen supply and ozonegenerator are switched off. Then the ozone destruct filter 36 isoperated, sucking in the ozone-containing gases, destroying the ozoneand issuing pure oxygen from it. The room can now be opened, theapparatus disconnected and loaded on the cart 48, and the room put backto its normal use.

EXPERIMENTAL EXAMPLES

Effective and optimum conditions for use in the present invention weredetermined using a laboratory apparatus as generally illustrated in FIG.4 of the accompanying drawings.

A single pure colony of Listerium monocytogenes was inoculated to aColumbia agar plate with 5% sheep's blood. They were incubated at 35° C.in room air for 18-24 hours. From the plate, 4-5 isolated colonies wereselected, and suspended in tryptic soy broth to achieve a 0.5 McFarlandturbidity standard (1.5×10⁸ cfu/ml) measured using a spectrophotometer.Inoculum was prepared by performing a series of serial dilutions of 0.9ml 0.85 NaCl broth with 0.1 ml of original 0.5 McFarland inoculum (6×10fold) to give solutions of 10⁻¹, 10⁻², 10⁻³, 10⁻⁴, 10⁻⁵, 10⁻⁶ and 10⁻⁷cfu/mL. Incubation of these serially diluted solutions and subsequentcounting of the resulting viable colonies determines the dilution atwhich growth is eliminated, to be expressed as a log kill. Thus, ifgrowth is eliminated at a three-fold (10⁻³ cfu/ml solution), this is alog 3 kill. This is standard procedure.

Organisms were plated out in triplicate, 0.1 ml of each solution beingspread over the surface of Columbia sheep's blood agar plates. Two setsof 12 plates were subjected to ozone/oxygen exposure at preselectedconcentrations of ozone (ppm), humidity and temperature conditions inthe illustrated apparatus. The other sets of 2 were treated as controls,with no ozone exposure, but kept at room temperature.

For ozone exposure, the apparatus generally illustrated in FIG. 4 wasused.

The test plates were mounted inside a disinfection chamber 60, theupstream end 62 of which had an ozone inlet port 64, a hydrogen peroxidevapor inlet port 65 and a water vapor inlet port 66. A cylinder 68 ofpressurized medical grade oxygen was provided, feeding oxygen to anozone generator 70, equipped with alternating current electrical platesto which variable voltage could be supplied via input control 72. Theoutput of oxygen/ozone mixed gas from the ozone generator 70 was fed tothe ozone inlet port 64 of the disinfection chamber 60. A water vaporhumidifier 74 supplied water vapor to inlet port 66. The disinfectionchamber 60 also contained a heater/cooler (not shown), a temperaturesensor 76, a pressure sensor 78, a humidity sensor 80 and an ozonesensor 82, connected electrically via respective lines 84, 86, 88 and 90to a control panel and monitor 92, connected to feed back to the oxygencylinder 68 to control flow for pressure adjustment purposes, to theozone generator 70 to control and adjust the ozone quantity, to thewater vapor humidifier 74 to control and adjust relative humidity in thedisinfection chamber 60, and to the heater/cooler to control and adjustthe temperature in the chamber. These parameters were all pre-set on thecontrol panel to desired values and automatically re-adjusted themselvesto these values as the experiments progressed.

An ozone destruct filter 94 was connected to the downstream end 96 ofthe disinfection chamber 60 at outlet port 98, to destroy ozone issuingfrom the chamber 60 at the end of the experiment. Gases were circulatedwithin the chamber 60, and expelled therefrom at the termination of theexperiment, using a fan 100 mounted therein. After placing the testplates in the chamber 60, it is sealed until the end of each experiment.

In a similar manner, test plates of Salmonella typhium were prepared,with the same serial dilutions, and exposed to ozone and hydrogenperoxide according to the invention

The control plates and the ozone treated plates were placed in anincubator at the same time. The plate counts were read through amicroscope, and the numbers of colony forming units on each plate wascounted.

Example 1

Table 1 below provides a summary of experiments, whereby combinations ofozone, H₂O₂, humidity and exposure time, at room temperature, wereevaluated in terms of the ability to eliminate Listerium monocytogenesisand Salmonella typhium when artificially applied as a biofilm ontonon-porous surfaces namely stainless steel discs. Columns A, B, C and Dare the counts at the serial dilutions 10⁻¹, 10⁻², 10⁻³ and 10⁻⁴respectively.

The steel discs for testing and the agar plates for testing wereprepared, exposed and tested as described in the previous Example, in anapparatus generally as illustrated in FIG. 4, with exposure conditionsshown in the Table 1 below.

TABLE 1 Ozone H202 EXP Run # Organism (PPM) (%) (min) Humidity Disc A BC D Control Listeria 0 0 0 0 1 TNTC 176 12 2 Control Listeria 0 0 0 0 2TNTC 123 17 1 Control Listeria 0 0 0 0 3 TNTC 189 15 0 1 Listeria 801.0% 30 80 4 0 0 0 0 1 Listeria 80 1.0% 30 80 5 0 0 0 0 1 Listeria 801.0% 30 80 6 0 0 0 0 2 Listeria 80 1.0% 45 80 7 0 0 0 0 2 Listeria 801.0% 45 80 8 0 0 0 0 2 Listeria 80 1.0% 45 80 9 0 0 0 0 3 Listeria 801.0% 60 80 10 0 0 0 0 3 Listeria 80 1.0% 60 80 11 0 0 0 0 3 Listeria 801.0% 60 80 12 0 0 0 0 4 Listeria 80 1.5% 60 80 13 0 0 0 0 4 Listeria 801.5% 60 80 14 0 0 0 0 4 Listeria 80 1.5% 60 80 15 0 0 0 0 ControlSalmonella 0 0 0 0 1 TNTC TNTC 112 26 Control Salmonella 0 0 0 0 2 TNTCTNTC 63 9 Control Salmonella 0 0 0 0 3 TNTC TNTC 77 4 1 Salmonella 801.0% 30 80 4 134 18 1 0 1 Salmonella 80 1.0% 30 80 5 161 13 0 0 1Salmonella 80 1.0% 30 80 6 112 15 3 0 1 Salmonella 80 1.0% 60 80 4 3 0 00 1 Salmonella 80 1.0% 60 80 5 5 0 0 1 1 Salmonella 80 1.0% 60 80 6 1 00 0

Example 2

Another series of experiments was conducted with the same Listeriamonocytogenes strain at room temperature, but deposited onto fibrouscarpet samples instead of steel discs. The Listeria carrying carpetsamples were suspended in a room as generally depicted in accompanyingFIG. 1, and the ozone/hydrogen peroxide/water disinfecting atmospherewas blown at the carpet surface with a fan directed at the carpet,causing physical agitation of the fibrous carpet surface. The agarplates for testing were prepared as previously described. Serialdilutions of 10-fold, 100-fold, 1000-fold and 10,000-fold were effectedand incubated. In duplicate runs using 80 ppm ozone, 1% hydrogenperoxide and 80% relative humidity, no viable colonies of Listeria weredetected, at any of the dilutions, whereas control, unexposed butcontaminated carpet samples had colonies too numerous to count.

Similarly, in duplicate runs with the same composition of atmosphere fora duration of 45 minutes, no viable colonies of Listeria were detectedat any of the dilutions.

Example 3

A further set of experiments was conducted using Listeria andSalmonella, which produced results which demonstrate efficacy at both 60ppm and 45 ppm ozone with 1% hydrogen peroxide and an exposure time of30 minutes at room temperature. In these runs the bacteria were exposedwithin biofilms on stainless steel discs only. This was done to bettermimic the type of material normally found in a government approved foodpreparation area, i.e. since one normally does not find fabrics in suchspaces. Should fabrics be present however, preferentially 80 ppm ofozone for at least 30 minutes (depending on the type of carpet present)should be used to achieve a 100% kill.

TABLE 2 Hu- Ozone H202 EXP mi- Run # Organism (PPM) (%) (min) dity A B CD Control Listeria 0 0 0 0 TNTC 176 12 2 Control Listeria 0 0 0 0 TNTC123 17 1 Control Listeria 0 0 0 0 TNTC 189 15 0 Control Listeria 0 0 0 0TNTC 135 5 0 Control Listeria 0 0 0 0 TNTC 186 9 1 1 Listeria 30 1.0% 3080 0 0 0 0 1 Listeria 30 1.0% 30 80 0 0 0 0 2 Listeria 45 1.0% 30 80 0 00 0 2 Listeria 45 1.0% 30 80 0 0 0 0 1 Listeria 45 1.0% 30 80 0 0 0 0 1Listeria 45 1.0% 30 80 0 0 0 0 2 Listeria 60 1.0% 30 80 0 0 0 0 2Listeria 60 1.0% 30 80 0 0 0 0 1 Listeria 80 1.0% 30 80 0 0 0 0 1Listeria 80 1.0% 30 80 0 0 0 0 2 Listeria 80 1.0% 45 80 0 0 0 0 2Listeria 80 1.0% 45 80 0 0 0 0 2 Listeria 80 1.0% 45 80 0 0 0 0 ControlSalmonella 0 0 0 0 TNTC 187 18 1 Control Salmonella 0 0 0 0 TNTC 86 6 0Control Salmonella 0 0 0 0 TNTC 94 3 1 Control Salmonella 0 0 0 0 TNTC193 18 0 Control Salmonella 0 0 0 0 TNTC 203 16 0 Control Salmonella 0 00 0 TNTC 172 19 2 1 Salmonella 30 1.0% 30 80 0 0 0 0 1 Salmonella 301.0% 30 80 0 0 0 0 2 Salmonella 45 1.0% 30 80 0 0 0 0 2 Salmonella 451.0% 30 80 0 0 0 0 1 Salmonella 45 1.0% 30 80 0 0 0 0 1 Salmonella 451.0% 30 80 0 0 0 0 2 Salmonella 60 1.0% 30 80 0 0 0 0 2 Salmonella 601.0% 30 80 0 0 0 0 1 Salmonella 80 1.0% 30 80 0 0 0 0 1 Salmonella 801.0% 30 80 0 0 0 0 2 Salmonella 80 1.0% 45 80 0 0 0 0 2 Salmonella 801.0% 45 80 0 0 0 0 2 Salmonella 80 1.0% 45 80 0 0 0 0

What is claimed is:
 1. A process of combating human-harmful, foodpoisoning-causing bacteria and spores thereof in an enclosed space andon surfaces within the space, consisting of: exposing the bacteria inthe space and on surfaces therein to a disinfecting atmosphere whichincludes ozone at an amount of 2-350 ppm by weight and hydrogen peroxideat an amount of 0.5-10 wt. %, at a relative humidity of at least 60%,and for a period of at least 30 minutes sufficient for an effective killof the bacteria and spores; wherein the amount of hydrogen peroxide isderived from a supply solution of 0.2%-10% hydrogen peroxide; andsubsequently removing ozone from the atmosphere, down to 0.04 ppm orless.
 2. The process of claim 1 wherein the amount ozone in thedisinfecting atmosphere is from 10-350 ppm.
 3. The process of claim 2wherein the amount ozone in the disinfecting atmosphere is from 20-200ppm.
 4. The process of claim 1 wherein the amount ozone in thedisinfecting atmosphere is from 20-100 ppm.
 5. The process of claim 2wherein the amount ozone in the disinfecting atmosphere is from 35-100ppm.
 6. The process of claim 1, wherein the hydrogen peroxide amount inthe disinfecting atmosphere is from 0.5-7%.
 7. The process of claim 6,wherein the hydrogen peroxide amount in the disinfecting atmosphere isfrom 1-5%.
 8. The process of claim 1, wherein the period of exposure isfrom about 30 minutes to about 120 minutes.
 9. The process of claim 8,wherein the period of exposure is from about 60 minutes to about 105minutes.
 10. The process of claim 1, wherein exposing the bacteria inthe space occurs while subjecting porous and fibrous surfaces within thespace to physical agitation while exposed to the disinfectingatmosphere.
 11. The process of claim 10 wherein the physical agitationis conducted with application of bristles.
 12. The process of claim 10wherein the physical agitation is conducted with application of airpressure jets.
 13. The process of claim 10 wherein the physicalagitation is conducted with application of ultrasonic energy, radiofrequency energy or electromagnetic waves, capable of causing physicaldisruption.
 14. The process of claim 1, wherein biofilm carryingsurfaces are exposed to a localized stream of the disinfectingatmosphere.
 15. The process of claim 14 wherein the localized stream isprovided at a pressure of from 14.7 to 100 psi.
 16. The process of claim1, wherein the bacteria is a Listeria species.
 17. The process of claim16, wherein the Listeria species is Listeria monocytogenes.
 18. Theprocess of claim 1, wherein the bacteria is a Salmonella species. 19.The process of claim 18, wherein the Salmonella species is eitherSalmonella typhimurium or Salmonella typhi.